1. Technical Field
This disclosure relates to organic EL devices which are able to convert electrical energy into light, and which have various applications in devices such as display devices, flat panel displays, backlights, illuminations, interior decorations, signboards, electronic cameras, timepieces, etc. More specifically, it relates to an integrated mask in which a plurality of deposition masks used for manufacturing the organic EL devices are arranged, and to a method and apparatus for fabricating the integrated mask. In addition, the disclosure also relates to a method and apparatus for manufacturing an organic EL device using the integrated mask.
2. Description of the Related Art
In organic EL devices, light is emitted when electrons supplied from cathodes and holes supplied from anodes are recombined inside an organic layer disposed between the cathodes and the anodes. Organic EL devices are usually used in thin, compact displays because of their simple structure and ability to emit high-intensity, multicolored light at low voltage.
In order to manufacture a full-color display panel using an organic EL device, thin film layers including red, green, and blue (RGB) emitting layers, a first electrode layer (for example, ITO), a second electrode layer (for example, metal), etc., must be regularly formed in a predetermined pattern with a predetermined pitch.
In the above-described thin film layers, in order to form organic thin film layers, for example, emitting layers, in a precise pattern, a mask deposition method is normally applied from the viewpoint of the characteristics of the organic thin film layers. In the mask deposition method, a deposition process is performed in a vacuum using a mask having apertures formed in accordance with a predetermined pattern of the emitting layer.
In order to increase the productivity in manufacturing the organic EL devices, multiple organic EL devices are simultaneously formed on a single, large substrate. This is because a mask deposition used for forming emitting layers is performed in a batch-wise manner, substrate by substrate, and the existing organic EL devices are mainly used in compact apparatuses.
In the case in which multiple organic EL devices are simultaneously formed on a single, large substrate, a deposition mask having a plurality of arrays of apertures, each array corresponding to a single organic EL device, must be prepared. However, in such a case, the size of such a deposition mask is increased, and the deposition mask is greatly deformed in the manufacturing process and the deposition process. Thus, the high dimensional accuracy of the arrays of apertures cannot be maintained sufficiently. Accordingly, an integrated mask in which a plurality of deposition masks, each of which has an array of apertures corresponding to a single organic EL device, are arranged is disclosed in Japanese Unexamined Patent Application Publication No. 2000-113978.
Since three emitting layers corresponding to three colors (RGB) are formed, it is important to accurately adjust the relative positions between the three emitting t layers. Although a method for positioning a single deposition mask relative to a substrate has been suggested (the Japanese Unexamined Patent Application Publication No. 11-158605), a method for positioning an integrated mask relative to a substrate has not been provided. In addition, in an integrated mask, a plurality of deposition masks provided for simultaneously forming multiple organic EL devices must all be accurately positioned.
Accordingly, it could be helpful to have a construction for practically using an integrated mask in which a plurality of deposition masks, each of which has an array of apertures corresponding to an organic EL device, are arranged. In addition, it could be helpful to have a means for fabricating the integrated mask in such a manner that the deposition masks are accurately positioned in the integrated mask. In addition, it could further be helpful to have a method and apparatus for manufacturing an organic EL device by which the integrated mask and a substrate can be accurately positioned, multiple organic EL devices can be formed on a single substrate by a deposition process, and the productivity in manufacturing organic EL devices can be significantly increased. Furthermore, it could be helpful to have a high-quality, inexpensive organic EL device.